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    <title>Preprocessor Directives and Macros</title>
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    <div class="refentry">
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      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="PreprocessorDirectivesandMacros"></a>
        <h1>Preprocessor Directives and Macros</h1>
        <p>
            Preprocessor Directives and Macros.
        </p>
      </div>
      <div class="refsect2">
        <a id="synopsis"></a>
        <h3>
        </h3>
        <div class="informaltable">
          <table border="0">
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              <col align="left" class="col1" />
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                <td align="left">
# <code class="function">pragma</code> <code class="varname">pp-tokens</code><sub>opt</sub> <span class="emphasis"><em>new-line</em></span>
                        </td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
          The preprocessing directives defined by the C99 specification are supported.
        </p>
        <p>
          A <code class="function"># pragma</code> directive where the preprocessing token
          <code class="constant">OPENCL</code> (used instead of <code class="constant">STDC</code>) does not
          immediately follow <code class="function">pragma</code> in the directive (prior to any macro
          replacement) causes the implementation to behave in an implementation-defined manner. The
          behavior might cause translation to fail or cause the translator or the resulting
          program to behave in a non-conforming manner. Any such <code class="function">pragma</code>
          that is not recognized by the implementation is ignored. If the preprocessing token
          <code class="constant">OPENCL</code> does immediately follow <code class="function">pragma</code> in the
          directive (prior to any macro replacement), then no macro replacement is performed on
          the directive, and the directive shall have one of the following forms whose meanings
          are described elsewhere:
        </p>
        <p>
</p>
        <div class="literallayout">
          <p>
            <code class="constant">          #pragma OPENCL <a class="citerefentry" href="FP_CONTRACT.html"><span class="citerefentry"><span class="refentrytitle">FP_CONTRACT</span></span></a> <em class="replaceable"><code>on-off-switch</code></em><br />
               <em class="replaceable"><code>on-off-switch</code></em>: one of ON OFF DEFAULT<br />
          #pragma OPENCL <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a> <code class="varname">extensionname : behavior</code><br />
          #pragma OPENCL <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a> all : <code class="varname">behavior</code></code>
          </p>
        </div>
        <p>
        </p>
        <p>
          The following predefined macro names are available.
        </p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem" style="list-style-type: disc"><code class="code">__FILE__</code> The presumed name of the current 
                 source file (a character string literal).
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__LINE__</code> The presumed line number (within the current source file)
                 of the current source line (an integer constant).
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__OPENCL_VERSION__</code> substitutes an integer reflecting the version
                 number of the OpenCL supported by the OpenCL device. The version of OpenCL
                 described in this document will have <code class="code">__OPENCL_VERSION__</code> substitute
                 the integer 200.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">CL_VERSION_1_0</code> substitutes the integer 100 reflecting the OpenCL 1.0 version.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">CL_VERSION_1_1</code> substitutes the integer 110 reflecting the OpenCL 1.1 version.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">CL_VERSION_1_2</code> substitutes the integer 120 reflecting the OpenCL 1.2 version.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">CL_VERSION_2_0</code> substitutes the integer 200 reflecting the OpenCL 2.0 version.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__OPENCL_C_VERSION__</code> substitutes an integer reflecting
                the OpenCL C version specified by the <code class="code">-cl-std</code> build option  to
                <a class="citerefentry" href="clBuildProgram.html"><span class="citerefentry"><span class="refentrytitle">clBuildProgram</span></span></a> or
                <a class="citerefentry" href="clCompileProgram.html"><span class="citerefentry"><span class="refentrytitle">clCompileProgram</span></span></a>. 
                If the <code class="code">-cl-std</code>
                build option is not specified, the highest OpenCL C 1.x 
                language version supported by each device is used 
                as the version of OpenCL C when compiling 
                the program for each device. The version of OpenCL C 
                described in this document will have 
                <code class="code">__OPENCL_C_VERSION__</code> substitute the integer 200 
                if <code class="code">–cl-std=CL2.0</code> is specified.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__ENDIAN_LITTLE__</code> is used to determine if the OpenCL device is a
                little endian architecture or a big endian architecture (an integer constant
                of 1 if device is little endian and is undefined otherwise). Also refer to
                <code class="constant">CL_DEVICE_ENDIAN_LITTLE</code> specified in the table of OpenCL
                Device Queries for 
                <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__kernel_exec(X, type<em class="replaceable"><code>n</code></em>)</code> (and
                <code class="code">kernel_exec(X, type<em class="replaceable"><code>n</code></em>))</code> is defined as
                follows:

                <p>
</p><div class="literallayout"><p>     <code class="code">__kernel __attribute__((work_group_size_hint(X, 1, 1)))</code> \<br />
              <code class="code">__attribute__((vec_type_hint(type<em class="replaceable"><code>n</code></em>)))</code></p></div><p>
                </p></li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__IMAGE_SUPPORT__</code> is used to determine if the OpenCL device supports
                images. This is an integer constant of 1 if images are supported and is undefined
                otherwise. Also refer to <code class="constant">CL_DEVICE_IMAGE_SUPPORT</code>
                specified in the table of OpenCL Device Queries for
                <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>.
            </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">__FAST_RELAXED_MATH__</code> is used to determine if the
                cl-fast-relaxed-math optimization option is specified in build options given
                to  <a class="citerefentry" href="clBuildProgram.html"><span class="citerefentry"><span class="refentrytitle">clBuildProgram</span></span></a> or
                <a class="citerefentry" href="clCompileProgram.html"><span class="citerefentry"><span class="refentrytitle">clCompileProgram</span></span></a>. 
                This is an integer constant of 1 if the cl-fast-relaxed-math build option 
                is specified and is undefined otherwise.
             </li>
            <li class="listitem" style="list-style-type: disc"><code class="code">CL_DEVICE_MAX_GLOBAL_VARIABLE_SIZE</code> 
                expands to a positive integer specifying the 
                maximum size in bytes for a program scope 
                variable or static function variable. This is the same 
                value as <code class="constant">CL_DEVICE_MAX_GLOBAL_VARIABLE_SIZE</code>
                returned by 
                <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a> 
                in table 4.3.
             </li>
            <li class="listitem" style="list-style-type: disc">
                The <code class="code">NULL</code> macro expands to a null pointer 
                constant. An integer constant expression with the 
                value 0, or such an expression cast to type 
                <code class="code">void *</code> is called a null pointer constant.
            </li>
            <li class="listitem" style="list-style-type: disc">
                The macro names defined by the C99 specification but not currently supported
                by OpenCL are reserved for future use.
            </li>
            <li class="listitem" style="list-style-type: disc">
                The predefined identifier <code class="code">__func__</code> is available.
            </li>
          </ul>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />

            <a href="https://www.khronos.org/registry/cl/specs/opencl-2.0-openclc.pdf#page=54" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="mathConstants.html"><span class="citerefentry"><span class="refentrytitle">Symbolic Math Constants</span></span></a>,
            <a class="citerefentry" href="clBuildProgram.html"><span class="citerefentry"><span class="refentrytitle">clBuildProgram</span></span></a>,
            <a class="citerefentry" href="FP_CONTRACT.html"><span class="citerefentry"><span class="refentrytitle">FP_CONTRACT</span></span></a>,
            <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2013 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
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